CD8+ T-cells play a crucial role in eradicating viral infections. The focus of this project is two-fold. First, to study general in vivo mechanisms of virus - host interactions and second, to understand how primary and memory T-cells respond to virus infection. Despite the importance of T-cells, we do not yet fully understand the induction of a CD8+ T-cell responses and the generation of CD8+ T-cell memory to virus infection. For viruses in which traditional vaccine approaches have not been successful, it is hoped that induction of CD8+ T-cell memory will enhance immunity. To induce optimal CD8+ T-cell responses to vaccines it is necessary to understand how primary CD8+ T-cells are stimulated. This project aims to address questions related to the optimal and activation of T cell immunity following primary and secondary virus infection by studying several viruses and different routes of infection. This year our studies examining a poxvirus skin infection have demonstrated distinct roles for innate and adaptive immune cells in virus clearance.